Preserved settled user and assistant component instances during compaction-only transcript rebuilds so warmed Markdown and layout caches remain valid.
Covered both manual and automatic compaction paths with focused regression tests.
Fixes#6033
- Added test coverage for auto-compaction entry warning attribution during dead-end scenarios.
- Verified automatic continuation and warning suppression when image-drop recovery successfully clears context pressure.
- Mocked session context usage and image-drop functionality to simulate high-usage state recovery.
executeCompaction added a transcript Spacer(1) the handoff path never adds; it leaked as an orphan blank line on cancelled/failed compaction (only the OK branch cleared it via rebuildChatFromMessages). Removed it, and on the OK branch the loader is stopped + statusContainer cleared before the rebuild so the live loader no longer composites over the reconciled transcript. The finally block stays as the idempotent cancel/fail safety net.